How to specify the input arguments description for custom tools #144
Description
I am testing this Python SDK using the step-5-build-an-interactive-assistant to create the weather app demo but I struggle to have the LLM understand that it has to provide some input to the get_weather tool.
For example, if I define the tool as in the example:
...
@define_tool(description="Get the current weather for a city")
async def get_weather(params: dict) -> dict:
print("weather tool called with params:", params)
....The AI calls the tool without specifying any city as input, so nothing is returned:
🌤️ Weather Assistant (type 'exit' to quit)
Try: 'What's the weather in Paris?' or 'Compare weather in NYC and LA'
You: What's the weather in Paris?
Assistant: weather tool called with params: {}
I'm unable to fetch the current weather for Paris right now due to a technical issue. Please try again later.
You: exitWhile, if I specify that an input argument should be provided:
@define_tool(description="Get the current weather for a city. The city name is provided in the 'city' parameter.")
async def get_weather(params: dict) -> dict:
print("weather tool called with params:", params)
if params is None or "city" not in params:
return {"error": "City parameter is required."}
...Then the tool gets that something is required as input:
You: What's the weather in Paris?
Assistant:
weather tool called with params: {}
I need to explicitly specify the city as "Paris" in the request. Let me try again with the correct parameter.
weather tool called with params: {'city': 'Paris'}
The current weather in Paris is 66°F and partly cloudy.
You: exitExpected behavior
In other MCP server tools descriptors, like C# ModelContextProtocol you can add a description for each input argument, something like:
[McpServerTool(Name = "SummarizeContentFromUrl"), Description("Summarizes content downloaded from a specific URI")]
public static async Task<string> SummarizeDownloadedContent(
McpServer thisServer,
HttpClient httpClient,
[Description("The url from which to download the content to summarize")] string url,
CancellationToken cancellationToken)
{
...Which allows the LLM to better understand the tool usage and expected parameters
Environment information
- Windows 11
- Python 3.14.0
- github-copilot-sdk==0.1.16
- GitHub Copilot CLI v0.0.392